Adds support HomeKit cameras!

pkg/srtp/server.go

@@ -0,0 +1,61 @@
+package srtp
+
+import (
+	"encoding/binary"
+	"net"
+)
+
+// Server using same UDP port for SRTP and for SRTCP as the iPhone does
+// this is not really necessary but anyway
+type Server struct {
+	sessions map[uint32]*Session
+}
+
+func (s *Server) AddSession(session *Session) {
+	if s.sessions == nil {
+		s.sessions = map[uint32]*Session{}
+	}
+	s.sessions[session.RemoteSSRC] = session
+}
+
+func (s *Server) RemoveSession(session *Session) {
+	delete(s.sessions, session.RemoteSSRC)
+}
+
+func (s *Server) Serve(conn net.PacketConn) error {
+	buf := make([]byte, 2048)
+	for {
+		n, addr, err := conn.ReadFrom(buf)
+		if err != nil {
+			return err
+		}
+
+		// Multiplexing RTP Data and Control Packets on a Single Port
+		// https://datatracker.ietf.org/doc/html/rfc5761
+
+		// this is default position for SSRC in RTP packet
+		ssrc := binary.BigEndian.Uint32(buf[8:])
+		session, ok := s.sessions[ssrc]
+		if ok {
+			if session.Write == nil {
+				session.Write = func(b []byte) (int, error) {
+					return conn.WriteTo(b, addr)
+				}
+			}
+
+			if err = session.HandleRTP(buf[:n]); err != nil {
+				return err
+			}
+		} else {
+			// this is default position for SSRC in RTCP packet
+			ssrc = binary.BigEndian.Uint32(buf[4:])
+			if session, ok = s.sessions[ssrc]; !ok {
+				continue // skip unknown ssrc
+			}
+
+			if err = session.HandleRTCP(buf[:n]); err != nil {
+				return err
+			}
+		}
+	}
+}

pkg/srtp/session.go

@@ -0,0 +1,97 @@
+package srtp
+
+import (
+	"github.com/AlexxIT/go2rtc/pkg/streamer"
+	"github.com/pion/rtcp"
+	"github.com/pion/rtp"
+	"github.com/pion/srtp/v2"
+)
+
+type Session struct {
+	LocalSSRC  uint32 // outgoing SSRC
+	RemoteSSRC uint32 // incoming SSRC
+
+	localCtx  *srtp.Context // write context
+	remoteCtx *srtp.Context // read context
+
+	Write func(b []byte) (int, error)
+	Track *streamer.Track
+}
+
+func (s *Session) SetKeys(
+	localKey, localSalt, remoteKey, remoteSalt []byte,
+) (err error) {
+	if s.localCtx, err = srtp.CreateContext(
+		localKey, localSalt, GuessProfile(localKey),
+	); err != nil {
+		return
+	}
+	s.remoteCtx, err = srtp.CreateContext(
+		remoteKey, remoteSalt, GuessProfile(remoteKey),
+	)
+	return
+}
+
+func (s *Session) HandleRTP(data []byte) (err error) {
+	if data, err = s.remoteCtx.DecryptRTP(nil, data, nil); err != nil {
+		return
+	}
+
+	packet := &rtp.Packet{}
+	if err = packet.Unmarshal(data); err != nil {
+		return
+	}
+
+	_ = s.Track.WriteRTP(packet)
+	//s.Output(core.RTP{Channel: s.Channel, Packet: packet})
+
+	return
+}
+
+func (s *Session) HandleRTCP(data []byte) (err error) {
+	header := &rtcp.Header{}
+	if data, err = s.remoteCtx.DecryptRTCP(nil, data, header); err != nil {
+		return
+	}
+
+	var packets []rtcp.Packet
+	if packets, err = rtcp.Unmarshal(data); err != nil {
+		return
+	}
+
+	_ = packets
+	//s.Output(core.RTCP{Channel: s.Channel + 1, Header: header, Packets: packets})
+
+	if header.Type == rtcp.TypeSenderReport {
+		err = s.KeepAlive()
+	}
+
+	return
+}
+
+func (s *Session) KeepAlive() (err error) {
+	var data []byte
+	// we can send empty receiver response, but should send it to hold the connection
+	rep := rtcp.ReceiverReport{SSRC: s.LocalSSRC}
+	if data, err = rep.Marshal(); err != nil {
+		return
+	}
+
+	if data, err = s.localCtx.EncryptRTCP(nil, data, nil); err != nil {
+		return
+	}
+
+	_, err = s.Write(data)
+
+	return
+}
+
+func GuessProfile(masterKey []byte) srtp.ProtectionProfile {
+	switch len(masterKey) {
+	case 16:
+		return srtp.ProtectionProfileAes128CmHmacSha1_80
+	case 32:
+		return srtp.ProtectionProfileAes256CmHmacSha1_80
+	}
+	return 0
+}